Problem: In the right triangle shown, $AC = 7$ and $BC = 3$. What is $AB$ ? $A$ $C$ $B$ $7$ $3$ $?$
We know $a^2 + b^2 = c^2$ We want to find $c$ ; let $a = 3$ and $b = 7$ So $c^2 = 3^2 + 7^2 = 58$ Then, $c = \sqrt{58}$.